1. Field of the Invention
The present invention relates generally to the design on integrated circuits generating reference voltages, and more specifically to a voltage reference with improved linearity addressing variable impedance characteristics at an output node.
2. Related Art
A voltage reference generally refers to a component that ideally provides a fixed output voltage (reference voltage). The output voltage may be provided at an output node of the voltage reference. The components/devices driven by the voltage reference are generally connected at the output node potentially by a conductive path.
A voltage reference is said to be linear if the output voltage provided by the voltage reference remains constant or varies in a proportionately linear fashion as the load current drawn from the voltage reference varies. In general, if it is known that the voltage reference varies in a proportionate fashion, appropriate correction techniques can be employed, as is well known in the relevant arts.
As is also well-known in the relevant arts, impedance characteristics (impedance, also termed “looking-in impedance”) at the output node are generally determined by the output impedance (which generally varies depending on the load current) of the voltage reference and the impedance of decoupling capacitor(s) typically connected at the output node of the voltage reference. The impedance characteristics at the output node cause variation in the output voltage based on the manner in which the load current drawn from the voltage reference varies.
Impedance characteristics at an output node of a voltage reference may vary on account of several factors. One factor contributing to such variation is the effective series resistance (ESR) of the decoupling capacitor (noted above), which may be different for different voltage references, at least across different fabrication/production batches. Due to the reasons noted above, impedance characteristics at the output node may vary. Thus, it may be difficult and/or inconvenient to provide a voltage reference with a desired minimum level of non-linearity.
Several aspects of the present invention provide a voltage reference with improved linearity addressing variable impedance characteristics at output node caused due to fabrication.
In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number.